Mine roof supports

ABSTRACT

A self-advancing mine roof support has at least two extensible hydraulic props, mounted on blocks of elastomeric material, and a prop aligning or positioning means. The latter comprises a retractable and extendable device operative between the props of the support so as to be responsive to angular movement thereof and operative or operable to give the props an initial setting attitude when the support has been relieved of the roof load. A preferred form of retractable and extendable device is a hydraulic ram having a pressure fluid cylinder attached to one prop and a piston working in said cylinder and acting substantially vertically on a foot or member projecting laterally from the other prop. A single prop aligning or positioning means may be arranged to align or position three, four or more props of a support.

United States Patent Whitaker 1 Mar. 7, 1972 [54] MINE ROOF SUPPORTS 3,484,071 12/1969 Wilkenloh et a1 ..248/357 [72] Inventor: Nllicltliael E. Whitaker, Altrincham, En- FOREIGN PATENTS OR pp -n an g 1,001,412 8/1965 Great Britain ..61/45 D 1 Asslgnw g E smiled, lnce, 8 1,160,389 H1964 Germany ..24s/354 ncas er, ng an 22 Filed: Mar. 31 1970 Primary Examiner-Dennis L. Taylor Attorney-Bennan, Davidson and Herman [211 App]. No.1 24,171

[57] ABSTRACT Foreign Application D8118 A self-advancing mine roof support has at least two extensible A r 8 1969 Great Britain 17 849/69 hydraulic props, mounted on blocks of elastomeric material, p and a prop aligning or positioning means. The latter comprises [52] U S Cl 61/45 248/357 a retractable and extenclable device operative between the [51] i 15/44 props of the support so as to be responsive to angular move- [58] Field oi Search .61/4s D; 299/31, 33; 248/357, 1"? Perable give the P 248/354 H 354 L 91/170 MP lmtlal setting attitude when the support has been relleved of the roof load. A preferred form of retractable and extendable [56] References Cited device is a hydraulic ram having a pressure fluid cylinder attached to one prop and a p1ston worklng 1n said cylinder and UNITED STATES PATENTS acting substantially vertically on a foot or member projecting laterally from the other prop. A single prop ahgmng or posigown t1on1ng means may be arranged to align or pos1tion three, four 1 1 annon e a or more re sofa su rt. 3,269,686 8/1966 Allen ..6l/45 D X p p ppo 3,309,054 3/1967 Davis-Ratclifi'e ..61/45 D X 8 Claims, 5 Drawing Figures PAIENTEBHAR (I972 I 3,646,768

sum 1 [IF 5 INVENTOR:

MICHAEL EVAN WHFfl/(ER,

4 TTORNEYS.

PATENTEDMAR 7 I972 SHEET l- UF 5 PATENTEUMAR 7 I972 SHEET 5 [IF 5 INVENTORi MICHAEL EV'QN WHITAKER,

' 4% Wm M MINE ROOF SUPPORTS This invention is for improvements in or relating to mine roof supports comprising a base or bases and at least two extensible props or legs mounted on said base or bases one behind or alongside the other and supporting a roof-engaging structure which is applied to the roof by extending the props and is lowered from the roof by retracting said props when it is required to advance the support towards themineral face. Such a support is hereinafter referred to as a support of the kind specified.

Advance of a support of the kind specified towards the mineral face is commonly effected by a hydraulic ram incorporated in it, the support then being known as a powered or self-advancing support.

Before resetting a support of the kind specified between floor and roof, after it has been advanced towards the mineral face, it is necessary to align or reposition the props if they have been tilted out of the vertical or out of some other desired angular attitude due, for example, to roof convergence or dragging of the roof-engaging structure against the roof during advance of the support.

According to the present invention there is provided a mine roof support at least two extensible props and prop aligning or positioning means comprising a retractable and extendable device operative between said props of the support so as to be responsive to angular movement thereof and operable to give the props an initial setting attitude when the support has been relieved of the roof load.

Conveniently the aligning or prop positioning means comprises a pressure-fluid cylinder attached to one prop or to a socket or housing therefor and a piston working in said cylinder and adapted to act on the other prop or on a housing or socket therefor. Alternatively, the aligning or prop positioning means may be a spring compressed or stretched between the two props or between housings, sockets or other members associated therewith and which take part in angular movement or tilting of the props.

The retractable and extendable device may be adapted to resist tilting of the props out of their initial setting attitude when the support is under load. For instance, where the retractable and extendable device is a pressure fluid ram a spring-loaded pressure relief valve may be included in the pressure fluid system of the ram.

Provision is, of course, made to enable the props to tilt on the base. Conveniently this is effected by mounting them in articulated housings or sockets. Such housings or sockets may, for example, be mounted on blocks or pads of rubber or other elastomeric material. Alternatively, ball-and-socket or other pivotal mounting devices may be provided for mounting the props or legs on the base or bases of the support so that they can tilt or be tilted thereon.

Similar provisions for articulation may be provided where the roof-engaging structure or canopy is mounted on the upper parts of the props or legs.

The prop aligning or positioning means according to the invention may be arranged so as to have the advantage of applying an equal resisting moment to both props using only one aligning device and in particular has the advantage of overcoming the present uneven loading of the rear leg without additional cost in the construction of the support.

Conveniently the prop aligning or positioning means comprises a pressure-fluid-operated rarn which acts downwardly or upwardly on a limb projecting laterally from the support.

One particular embodiment of the invention will now -be described, by way of example, with reference to the accompanying drawing in which:

FIG. 1 shows, in side elevation, the rear and front prop or leg of a support in their vertical attitude, in which attitude they are, in this particular case, initially set between floor and roof.

FIG. 2 shows the tilting of the legs from the vertical attitude due, for example, to roof convergence or the roof-engaging structure dragging against the roof during advance of the support, and

FIGS. 3, 4 and 5 are a sectional side elevation on the line V-V of FIG. 4, plan and front elevation respectively of a modification in which a single aligning or positioning device serves four props of a support.

The support shown on the drawings comprises a base 10 having mounted on it at least two side-by-side pairs of hydraulically extensible telescopic props, each pair comprising a rear prop and a forward prop. Only one pair of such props is shown on the drawings, the reference numeral 11 indicating the rear prop and the reference numeral 12 the forward prop. These pairs of props support and apply a roof-engaging structure (e.g., a canopy or roof-bars), not shown, to the roof.

The rear prop 11 is positioned in a tubular socket or housing 13 having a laterally projecting foot 14, for a purpose hereinafter to be described, secured on a plate 15.

The plate 15 is mounted on a slab or pad of rubber l6 sandwiched between the plate 15 and the base 10 of the support. This slab of rubber may be prestressed (compressed) to a desired degree by means of bolts which pass through aligned holes in the plate 15, slab l6 and the base 10. The centers of these holes are indicated at 17.

The front leg 12 is positioned in a tubular socket or housing 18 seated on, and attached to a plate 19 mounted on a rubber slab or pad 20 sandwiched between the plate 19 and the base 10 of the support. The pad of rubber 20 may be prestressed (compressed) to a desired degree by means of bolts passed through aligned holes in the plate 19, slab 20 and the base 10, the centers of these bolt holes being indicated at 21.

For the purpose of the present invention the cylinder 22 of an aligning or positioning device for the props 11 and 12 is secured to the socket 18 for the prop 12. A piston which works in the cylinder 22 has a piston rod 23 provided with a rounded or convex end 24 which bears against the laterally extended part 25 of the plate 15 to which the foot 14 of the socket 13 is secured. A hydraulic pressure-fluid supply and discharge pipe 26 is connected to the cylinder 22.

A manually operable valve may be included in this pipe so that pressure fluid can be fed to or discharged from the ram cylinder 22 so as to set the props manually in a required attitude.

As shown in FIG. 1, the props of the support have been set vertically between floor and roof. FIG. 2 shows how, due for example to roof convergence or drag of the roof-engaging structure against the roof during advance of the support, the props have been tilted out of the vertical. The aligning devices 22, 23 may be arranged to resist this tilting of the props and such an arrangement has, in accordance with the invention, the advantage of applying an equal resisting moment to all four props at the rear of the support using only two rams or aligning devices 22, 23.

During advance and resetting of the support pressure-fluid is supplied to each ram 22, 23 so that it acts to align the props, i.e., restore them to their vertical attitude.

The pipe 26 may be connected in the hydraulic system of the advancing ram of the support so that as the support is advanced the props are simultaneously aligned.

in some circumstances it may be required that the props should not be set vertically but should be set in an attitude leading towards the face. This may be effected by increasing the projection of the piston 23 so that the plates 15 and 19 are depressed below the horizontal as shown in chain lines in FIG. 1. It will be appreciated that as the piston rod 23 pivots at 24 on the extension 25 of the plate 15 and as the cylinder 22 is at tached to the socket 18, said socket l8 and the socket 13 will tilt simultaneously and similarly under the action of the ram 22, 23.

A pressure relief valve may be incorporated, if required, in the hydraulic system of the ram 22, 23.

One ram or aligning device, 22, 23 can be used to align or position all four of the props or legs or more if provided in the support. For example, as shown in FIGS. 3, 4 and 5, the cylinder 22 of a single ram is attached by a frame 27 to the front props 12 and the piston of said ram acts on a yoke 28 the ends of which are attached to the extended parts 25 of the plates 15. lclaim:

l. A mine roof support including a base, at least two spacedapart prop-holding devices mounted on said base by means which provide for tilting of said prop-holding devices relatively to the base, an extensible prop in each of said prop-holding devices and a force responsive and force applying device having relatively contractable and extensible parts, one of said parts engaging one of said prop-holding devices and the other of said parts engaging the other of said prop-holding devices, whereby said force responsive and force applying device responds to said tilting of the prop-holding devices and is operative to apply a force simultaneously to said prop-holding devices to give the props therein an initial setting attitude when the support has been relieved of the roof load.

2. A mine roof support as claimed in claim 1 wherein said force responsive and force applying device responds re sistingly to tilting of the prop holding devices.

3. A mine roof support as claimed in claim 1 wherein the force responsive and force applying device comprises a pressure-fluid ram having its cylinder attached to one of the propholding devices and its piston engaging the other prop-holding device.

4. A mine roof support as claimed in claim I wherein each prop-holding device is mounted on a block of elastomeric material for tilting movement relatively to the base.

5. A mine roof support as claimed in claim 1 wherein one of the prop-holding devices has a laterally projecting member which is engaged by one of said parts of the force responsive and force applying device.

6. A mine roof support as claimed in claim 3 wherein said pressure fluid ram is connected in the pressure fluid system of a pressure-fluid advancing ram for the support whereby as the support is advanced the props are simultaneously given their initial setting attitude.

7. A mine roof support as claimed in claim 3 wherein a pres sure relief valve is incorporated in the pressure fluid system of said ram.

8. A mine roof support as claimed in claim 1 and having at least three prop-holding devices, an extensible prop in each of said prop-holding devices and a force responsive and force applying device common to all said prop-holding devices, said force responsive and force applying device having one of its said parts engaging at least one of said prop-holding devices and the other of its said parts engaging a laterally projecting member of the remaining props. 

1. A mine roof support including a base, at least two spacedapart prop-holding devices mounted on said base by means which provide for tilting of said prop-holding devices relatively to the base, an extensible prop in each of said prop-holding devices and a force responsive and force applying device having relatively contractable and extensible parts, one of said parts engaging one of said prop-holding devices and the other of said parts engaging the other of said prop-holding devices, whereby said force responsive and force applying device responds to said tilting of the prop-holding devices and is operative to apply a force simultaneously to said prop-holding devices to give the props therein an initial setting attitude when the support has been relieved of the roof load.
 2. A mine roof support as claimed in claim 1 wherein said force responsive and force applying device responds resistingly to tilting of the prop holding devices.
 3. A mine roof support as claimed in claim 1 wherein the force responsive and force applying device comprises a pressure-fluid ram having its cylinder attached to one of the prop-holding devices and its piston engaging the other prop-holding device.
 4. A mine roof support as claimed in claim 1 wherein each prop-holding device is mounted on a block of elastomeric material for tilting movement relatively to the base.
 5. A mine roof support as claimed in claim 1 wherein one of the prop-holding devices has a laterally projecting member which is engaged by one of said parts of the force responsive and force applying device.
 6. A mine roof support as claimed in claim 3 wherein said pressure fluid ram is connected in the pressure fluid system of a pressure-fluid advancing ram for the support whereby as the support is advanced the props are simultaneously given their initial setting attitude.
 7. A mine roof support as claimed in claim 3 wherein a pressure relief valve is incorporated in the pressure fluid system of said ram.
 8. A mine roof support as claimed in claim 1 and having at least three prop-holding devices, an extensible prop in each of said prop-holding devices and a force responsive and force applying device common To all said prop-holding devices, said force responsive and force applying device having one of its said parts engaging at least one of said prop-holding devices and the other of its said parts engaging a laterally projecting member of the remaining props. 